In eukaryotic organisms,cell sizes are normally maintained at a stable level specific to species and cell types.However,the orig-inal sizes of two daughter cells are not always equal right after mitosis.In the Arabidopsis shoot apical meristem,besides sym-metric division,asymmetric division generates a large daughter cell and a small daughter cell.If these two daughter cells go through the progression of a cell cycle within the same time course,one would expect an enhanced variability of cell sizes throughout the meristem.In fact,the cell size variability is cor-rected by adjusting different growth periods before the large and small daughter cell divide.How cells sense their own sizes and control the progression through cell cycles remains unclear.